Gallium nitride (GaN)-based materials have several advantages on electrical, mechanical and chemical properties, such as wide band gap, high breakdown voltage, high electron mobility, large elastic modulus, high piezoelectric and piezoresistive coefficients, etc., as well as chemical inertness. Such advantages make GaN-based materials attractive for making devices such as high brightness light-emitting diodes (LEDs), power switching devices, regulators, battery protectors, panel display drivers, telecommunication devices, etc.
In addition, progress made in designs and manufacturing of Si-based devices and electronics in the past several decades has demonstrated the unsurpassed levels of scaling capability and circuit complexity of Si-base devices. As a result, it's desirable to integrate GaN-based devices with Si-based devices on the same chip to allow enhanced functionalities and design flexibility for advanced applications. Devices made with GaN-based materials are often formed on sapphire substrates or SiC substrates. It is within this context the following disclosure arises.